1. Field of the Invention
The present invention relates generally to a web splicing apparatus for splicing webs, and more particularly to a splicing method and apparatus for splicing ends of long flexible sheet materials such as plastic film, paper and foil (hereinafter referred to as "web") unwound from an old roll and a new roll.
2. Description of Related Art
U.S. Pat. No. 3,654,035, which corresponds to Japanese Patent Publication No. 48-38461, and Japanese Patent Publication No. 49-12329 disclose pieces of conventional web splicing apparatus consisting of a web turret, a web cutting and splicing unit, and so forth.
The turret has a turret arm, and an old roll and a new roll are pivotally supported by ends of the turret arm. The web is continuously supplied to the cutting and splicing unit by changing the positions of the old roll and the new roll. The cutting and splicing unit has a cutting drum and a splicing drum. The cutting drum cuts the trailing end of an old web which is being unwound from the old roll and the leading end of a new web which starts to be unwound from the new roll. The splicing drum splices the web ends with splicing tape.
Japanese Patent Publication No. 60-56614 discloses a web splicing apparatus in which a vacuum box is arranged between the turret arm and the cutting and splicing unit. In this web splicing apparatus, a scrap cut from the old web by the cutting and splicing unit is sucked into the vacuum box, and then the scrap is discharged to the outside of the vacuum box.
The above-described pieces of web splicing apparatus, however, have a disadvantage in that when the trailing end of the old web separates from the core of the old roll, the trailing end comes loose, and therefore a part of the old web from the trailing end to the cutting and splicing unit drifts. Consequently, when the trailing end of the old web reaches the web splicing position, the splicing does not take place at a proper position.